1. Field of the Invention
The present invention relates to an imaging apparatus and an imaging method, and specifically, to an imaging apparatus having an optical-multiplex system using an image sensor that photoelectrically converts light from an object and an imaging method therefor.
2. Description of Related Art
As imaging apparatus, a pinhole camera that performs imaging by guiding light from an object through a hole called a pinhole pierced on one surface of a dark box onto a photoreceptor such as a film within the dark box is widely known.
In the case of the pinhole camera, the light reaching one point of the photoreceptor is only a little light that has passed through the pinhole.
Therefore, the amount of light is small, and the pinhole camera is impractical especially in consideration of imaging in a dark place.
Accordingly, in a general imaging apparatus, an imaging lens is used and an imaging device is provided in a focal position of the imaging lens.
Further, optical processing is performed on the light from the object introduced by the imaging lens in an optical system for easy conversion into electric signals by the imaging device. Then, the light is guided to the photoelectric conversion side of the imaging device 102, and predetermined signal processing is performed on the electric signals obtained by the photoelectric conversion by the imaging device by a downstream signal processing circuit (for example, Non-Patent Document 1 (Hiroo Takemura, CCD camera gijutsu nyuumon, first edition, CORONA PUBLISHING, August 1998, pp. 2-4)).
Recently, the imaging apparatus of this kind has not only been used singly as a camera system such as a digital still camera or the like but also has been incorporated into a small portable apparatus such as a cellular phone or the like for use.
Accordingly, for incorporation into the cellular phone or the like, currently, a smaller and lighter imaging apparatus at lower cost is strongly desired.
That is, incorporation of the smaller and lighter imaging apparatus at lower cost may greatly contribute to provide a smaller and lighter small portable apparatus of lower cost such as a cellular phone or the like.
However, an imaging apparatus using an imaging lens becomes larger by the size of the imaging lens, heavier by the weight of the imaging lens, and further, becomes expensive due to the cost of the imaging lens.
Further, the light falls off at edges by shading of the imaging lens. Furthermore, for imaging of an object having a wide dynamic range, a large difference in amount of signal charge is produced between pixels of the imaging device, and it is necessary to design the dynamic range of the imaging device wider in consideration of the difference.
In response to the circumferences, Patent Document 1 (JP-A-2006-87088) proposes an optical-multiplex system imaging apparatus that can be made smaller and lighter with lower cost without using an imaging lens and can perform imaging of images without blur using a desired amount of light.